RFI hais txog qhov tsis xav tau hluav taws xob hluav taws xob nyob hauv ntau zaus thaum nws tsim tawm hauv xov tooj cua sib txuas lus.Qhov ntau zaus ntawm qhov tshwm sim tshwm sim ntawm 10kHz txog 30MHz;Qhov ntau zaus ntawm qhov tshwm sim hluav taws xob yog nyob nruab nrab ntawm 30MHz thiab 1GHz.
Muaj ob lub laj thawj vim li cas RFI yuav tsum tau txiav txim siab: (1) Lawv cov khoom yuav tsum ua haujlwm ib txwm nyob hauv lawv qhov chaw ua haujlwm, tab sis qhov chaw ua haujlwm feem ntau nrog RFI hnyav.(2) Lawv cov khoom tsis tuaj yeem tawm RFI kom ntseeg tau tias lawv tsis cuam tshuam nrog RF kev sib txuas lus uas tseem ceeb rau kev noj qab haus huv thiab kev nyab xeeb.Txoj cai lij choj tau muab kev txhawb nqa kev sib txuas lus RF kom ntseeg tau tias RFI tswj cov khoom siv hluav taws xob.
RFI kis tau los ntawm hluav taws xob (electromagnetic tsis nyob rau hauv qhov chaw dawb) thiab kis tau los ntawm cov teeb liab kab thiab AC fais fab system.
Radiation - ib qho tseem ceeb tshaj plaws ntawm RFI hluav taws xob los ntawm cov khoom siv hluav taws xob yog AC fais fab.Vim tias qhov ntev ntawm AC fais fab kab mus txog 1/4 ntawm qhov sib thooj ntawm cov khoom siv digital thiab cov khoom siv hluav taws xob hloov pauv, qhov no yog lub kav hlau txais xov zoo.
Kev coj-RFI yog ua nyob rau hauv ob hom ntawm AC fais fab mov system.Cov yeeb yaj kiab (asymmetric) RFI tshwm sim hauv ob txoj hauv kev: ntawm kab hauv av (LG) thiab nruab nrab hauv av (NG), thaum sib txawv hom (symmetric) RFI tshwm rau ntawm kab nruab nrab kab (LN) hauv daim ntawv ntawm qhov hluav taws xob.
Nrog txoj kev loj hlob sai ntawm lub ntiaj teb niaj hnub no, ntau thiab ntau lub zog hluav taws xob hluav taws xob tau tsim tawm.Nyob rau tib lub sijhawm, ntau thiab ntau lub zog hluav taws xob qis dua yog siv rau cov ntaub ntawv xa mus thiab kev ua haujlwm, kom nws ua rau muaj kev cuam tshuam ntau dua thiab txawm tias lub suab nrov cuam tshuam rau cov khoom siv hluav taws xob.Cov kab hluav taws xob cuam tshuam cov lim dej yog ib qho tseem ceeb ntawm kev lim dej siv los tswj RFI los ntawm cov khoom siv hluav taws xob nkag mus rau (cov khoom siv muaj peev xwm ua tsis tau) thiab tawm mus (muaj peev xwm cuam tshuam rau lwm lub tshuab lossis RF kev sib txuas lus).Los ntawm kev tswj RFI rau hauv lub hwj chim ntsaws, lub hwj chim kab lim kuj tseem cuam tshuam cov hluav taws xob ntawm RFI.
Cov kab hluav taws xob lim dej yog ib qho kev sib txuas ntau hauv network passive tivthaiv, uas yog teem rau hauv ob chav qis channel lim qauv.Ib lub network yog siv rau kev sib txawv hom attenuation, thiab lwm yam yog rau txawv hom attenuation.Lub network muab RF zog attenuation nyob rau hauv "nres band" (feem ntau ntau tshaj 10kHz) ntawm lub lim, thaum tam sim no (50-60Hz) yog qhov tseem ceeb tsis attenuated.
Raws li ib qho kev sib txuas thiab kev sib txuas ob sab, cov kab hluav taws xob cuam tshuam cov lim dej muaj cov yam ntxwv hloov pauv yooj yim, uas zoo heev nyob ntawm qhov chaw thiab qhov load impedance.Lub attenuation yam ntxwv ntawm lub lim yog qhia los ntawm tus nqi ntawm cov yam ntxwv hloov dua siab tshiab.Txawm li cas los xij, nyob rau hauv ib puag ncig kab hluav taws xob, qhov chaw thiab qhov chaw thauj khoom impedance tsis meej.Yog li, muaj ib txoj hauv kev los txheeb xyuas qhov sib xws ntawm cov lim hauv kev lag luam: ntsuas qhov attenuation theem nrog 50 ohm resistive qhov chaw thiab qhov kawg load.Tus nqi ntsuas tau txhais tau tias yog qhov poob qis (IL) ntawm lub lim:
I..L.= 10 log * (P(l)(Ref)/P(l))
Ntawm no P (L) (Ref) yog lub hwj chim hloov los ntawm lub hauv paus mus rau lub load (tsis muaj lim);
P (L) yog lub zog hloov dua siab tshiab tom qab tso cov lim dej ntawm qhov chaw thiab cov khoom thauj.
Qhov kev poob qis kuj tseem tuaj yeem qhia tau hauv qhov voltage lossis tam sim no piv:
IL = 20 log *(V(l)(Ref)/V(l)) IL = 20 log *(I(l)(Ref)/I(l))
Ntawm no V (L) (Ref) thiab I (L) (Ref) yog qhov ntsuas qhov ntsuas tsis muaj lim,
V (L) thiab I (L) yog ntsuas qhov tseem ceeb nrog lim.
Qhov kev poob qis, uas tsim nyog sau cia, tsis sawv cev rau RFI attenuation kev ua tau zoo los ntawm cov lim dej hauv ib puag ncig ntawm lub zog.Nyob rau hauv ib puag ncig ntawm lub hwj chim kab, tus nqi txheeb ze ntawm qhov chaw thiab qhov load impedance yuav tsum tau kwv yees, thiab cov qauv lim tsim nyog raug xaiv los ua kom qhov siab tshaj plaws impedance tsis sib haum ntawm txhua lub davhlau ya nyob twg.Lub lim yog nyob ntawm qhov kev ua tau zoo ntawm lub davhlau ya nyob twg impedance, uas yog lub hauv paus ntawm lub tswv yim ntawm "mismatch network".
Kev ntsuas kev ntsuas yuav tsum muaj qhov chaw nyob ntsiag to RF - lub plhaub tiv thaiv - kab impedance stabilization network, thiab RF voltage ntsuas (xws li FM receiver lossis spectrum analyzer).RF ib puag ncig ntawm qhov kev xeem yuav tsum yog tsawg kawg hauv qab qhov kev txwv tshwj xeeb ntawm 20dB txhawm rau kom tau txais cov txiaj ntsig kev xeem raug.Ib qho linear impedance stabilization network (LISN) yog xav tau los tsim kom muaj qhov xav tau qhov impedance rau cov tswv yim ntawm cov kab hluav taws xob, uas yog ib feem tseem ceeb ntawm qhov kev sim ntsuas vim tias qhov impedance cuam tshuam ncaj qha rau qhov ntsuas hluav taws xob.Tsis tas li ntawd, qhov tseeb broadband ntsuas ntawm lub receiver kuj yog ib qho tseem ceeb parameter ntawm qhov kev xeem.
Lub sij hawm xa tuaj: Mar-30-2021
